Blood pressure lowering n-pyridyl-, n-quinolyl-, and n-piperdyl-n-acyl amino acid derivatives and method

ABSTRACT

Compounds of the structure: ##STR1## wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  are hydrogen, alkyl, alkenyl, alkynyl, phenyl-alkyl, or cycloalkyl, 
     n is an integer from 0 to 4 inclusive, 
     M is heterocyclic or heterocyclic alkyl, 
     Y is hydroxy, alkoxy, amino, or substituted amino, amino-alkanoyl, aryloxy, aminoalkoxy, or hydroxyalkoxy, and 
     R 7  is hydrogen, alkanoyl, carboxylalkanoyl, hydroxyalkanoyl, amino-alkanoyl, cyano, amidino, carbalkoxy, ZS, or ##STR2##  wherein Z is hydrogen, alkyl, hydroxyalkyl, aminoalkyl or the radical ##STR3##  wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , n, M and Y are as described above; and where Y is hydroxy their nontoxic, pharmaceutically acceptable alkali metal, alkaline earth metal, and amine salts. 
     These compounds possess antihypertensive and angiotensin converting enzyme inhibitory activity.

This application is a division of copending application Ser. No.323,852, filed Nov. 23, 1981, now U.S. Pat. No. 4,507,312, which is adivision of application Ser. No. 200,180, filed Oct. 24, 1980, now U.S.Pat. No. 4,304,771, issued Dec. 8, 1981, which was acontinuation-in-part of application Ser. No. 057,175, filed July 13,1979, now U.S. Pat. No. 4,256,761, issued Mar. 17, 1981.

This invention relates to new chemical compounds having valuablepharmaceutical activity. It particularly relates to amides havingantihypertensive and angiotensin converting enzyme inhibitory activityand of the structure ##STR4## wherein R₁, R₂, R₃, R₄, R₅, and R₆ arehydrogen, alkyl, alkenyl, alkynyl, phenyl-alkyl, and cycloalkyl, and maybe the same or different,

n is an integer from 0 to 4 inclusive,

M is heterocyclic or heterocyclic alkyl,

Y is hydroxy, alkoxy, amino, or substituted amino, amino-alkanoyl,aryloxy, aminoalkoxy, or hydroxyalkoxy, and

R₇ is hydrogen, alkanoyl, carboxyalkanoyl, hydroxyalkanoyl,aminoalkanoyl, cyano, amidino, carbalkoxy, ZS, or ##STR5## wherein Z ishydrogen, alkyl, hydroxyalkyl, aminoalkyl or the radical ##STR6##wherein R₁, R₂, R₃, R₄, R₅, R₆, n, M and Y are as described above; andwhere Y is hydroxy, their nontoxic, pharmaceutically acceptable alkalimetal, alkaline earth metal, and amine salts.

The alkyl groups per se and in the alkyl moiety in aralkyl,cycloalkyl-alkyl, polycycloalkyl-alkyl, heteroaryl-alkyl and the like,and, in alkoxy, alkylthio, alkanoyl, carbalkoxy, and alkylamino, may bestraight-chained or branched and are preferably lower alkyl groupscontaining from 1 to 6 carbons. Such groups include methyl, ethyl,propyl, isopropyl, butyl, isobutyl, amyl, iso-amyl, hexyl, and the like.

The alkenyl and alkynyl groups may also be branched or straight-chainedand contain from 2 to 6 carbon atoms. Such groups include vinyl,ethynyl, propenyl, allyl, isopropenyl, and the like.

The cycloalkyl groups may be mono or polycyclic and contain from 3 to 16carbon atoms. The M heterocyclic groups may be mono or polycyclic andinclude such groups as pyridyl, quinolyl, piperidyl, pyrrolyl,morpholinyl, thiomorpholinyl, furyl, furfuryl, tetrahydrofurfuryl,thienyl, tetrahydrothienyl, imidazolyl, benzimidazolyl, and the like.These groups may carry substituents such as alkyl, alkenyl, alkynyl,hydroxy, thio, amino, alkylamino, dialkylamino, alkoxy, alkylthio, andhalo. The sulfur in the tetrahydrothienyl may be oxidized to thesulfone.

The preferred compounds are those wherein R₁, R₃, R₄, R₅ and R₆ arehydrogen, R₂ is lower alkyl, preferably methyl, R₇ is hydrogen or loweralkanoyl, n is 1, Y is hydroxy, and M is thienyl, tetrahydrothienyl, andtetrahydrothienyl-sulfone.

The compounds of the present invention are prepared by the reaction ofan appropriately substituted amino acid ester of the structure ##STR7##with a carboxylic acid of the structure ##STR8## followed by thestepwise hydrolysis of (i) the ester to yield the free carboxylic acidand (ii) the acetyl group to yield the free thiol, providing a compoundof the structure ##STR9## In these formulae, R is lower alkyl,preferably t-butyl and R₁, R₂, R₃, R₄, R₅, R₆, M and n are as definedabove.

It is known to those skilled in the art that those amides of the presentinvention having an asymmetric carbon atom may exist in racemic oroptically active levo or dextro forms. All of these forms arecontemplated within the scope of this invention.

The invention will be more fully illustrated in the examples whichfollow. These examples are given by way of illustration and are not tobe considered as limiting.

EXAMPLE 1 t-Butyl bromoacetate

Bromoacetic acid (484 g, 3.48 mol) was dissolved in methylene chloride(1000 ml) and concentrated sulfuric acid (5 ml) was added as catalyst.The resulting solution was cooled in a dry-ice acetone bath andisobutylene was bubbled through the solution for an hour and a half. Theflask was lightly stopped with a gas venting stopper and allowed tostand at room temperature overnight. Aqueous potassium carbonate (10%)was added and the layers were separated. The aqueous layer was discardedand the organic layer was washed once more with aqueous potassiumcarbonate (10%), once with water, dried over magnesium sulfate, andfiltered. Evaporation of the solvent afforded t-butyl bromoacetate as apale yellow oil (600 g, 88.4%).

EXAMPLE 2 2-Acetylthio-1-methylpropionic acid

Thiolacetic acid (1000 g, 13.2 mol) was placed in a five-liter roundbottom flask and cooled in an ice bath. Methacrylic acid (610 g, 7.09mol) was added with vigorous stirring. Cooling was continued for fifteenminutes and then the reaction mixture was heated to a gentle reflux forone hour. Stirring was continued at room temperature for six days.Excess thiolacetic acid was removed in vacuo and the residue wasdissolved in chloroform. The chloroform was washed four times with waterand dried over magnesium sulfate. Filtration and evaporation of thesolvent yielded a yellowish-orange oil which was vacuum distilled at100° C. to give the product initially as a yellow oil which slowlycrystallized. Addition of ether and filtration of the product afforded apale yellow solid (890 g, 77.5%), m.p. 35°-37°.

EXAMPLE 3 2-Acetylthio-1-methylpropionyl chloride

2-Acetylthio-1-methylpropionic acid (6.3 g, 0.0389 mol) was dissolved intoluene (50 ml) and five drops of pyridine was added. Thionyl chloride(10 ml) was added in one portion and the resulting mixture was stirredat room temperature for one and a half hours. The toluene was evaporatedon a rotary evaporator and water was added to the residue. The productwas extracted three times with chloroform. The combined chloroformextract was washed twice with 5% sodium bicarbonate and twice withwater. The chloroform was dried over magnesium sulfate, filtered andevaporated to afford (6.9 g, 98.3%) of the product as a pale yellow oil.

EXAMPLE 4 N-(3-Acetylthio-2-methylpropanoyl)-N-tetrahydrofurfurylglycinetert-butyl ester

To a solution of N-tetrahydrofurfurylglycine tert-butyl ester (6.6 g,0.0307 mol) and 3-acetylthio-2-methylpropionic acid (5.3 g, 0.0307 mol)in dry methylene chloride (150 ml) chilled in an ice bath was addeddicyclohexylcarbodiimide (6.7 g, 0.0325 mol). The resulting mixture wasstirred with cooling for 30 minutes and then overnight at roomtemperature. Precipitated dicyclohexylurea was filtered and washed witha small amount of methylene chloride. Concentration of the filtrateafforded crude product as a thick yellow oil which was used withoutfurther purification.

EXAMPLE 5 N-(3-mercapto-2-methylpropanoyl)-N-tetrahydrofurfurylglycine

Anhydrous ammonia was bubbled for fifteen minutes through methanol (150ml) and the resulting ammonia saturated solution was added in oneportion toN-(3-acetylthio-2-methylpropanoyl)-N-tetrahydrofurfurylglycine (7 g,0.0231 mol) and the system was placed under a slight pressure ofnitrogen. The resulting solution was stirred at room temperature for twohours. The solvent was removed in vacuo and the residue was applied to acolumn of AG-50W-X2 (Bio-Rad Laboratories) cation exchange resin andeluted with methanol. Methanol was evaporated and the residue wasdissolved in chloroform. The chloroform was washed once with water anddried over magnesium sulfate. Filtration and evaporation of the solventafforded a yellowish-orange oil which was purified by HPLC using thefollowing solvent system: ethyl acetate/n-hexane/acetic acid (40:60:1).In this manner pure product was obtained as a colorless oil (3.9 g,64%). The product was characterized as its DCHA salt, recrystallizedfrom isopropanol, m.p. 128°-130° C.

EXAMPLE 6 N-(3-Pyridylmethylene)glycine ethyl ester

Glycine ethyl ester hydrochloride (42.1 g, 0.302 mole) were dissolved inmethanol (500 ml) in a one-liter round bottom flask which contained astirring bar and a nitrogen inlet. Concentrated hydrochloric acid wasadded dropwise to pH 0 and the resulting solution was stirred at roomtemperature for 30 minutes. Sodium cyanoborohydride (15 g, 0.239 mole)was then added portionwise over 30 minutes. The resulting mixture wasstirred for 21/2 hours at room temperature while periodically checkingthe pH of the mixture. The pH was kept at 0 to 3 by the dropwiseaddition of hydrochloric acid. Most of the methanol was evaporated togive a yellow pasty residue. Water was added to the residue and themixture was basified to pH 8-9 with concentrated ammonium hydroxide. Theproduct was extracted several times into chloroform and the combinedchloroform extracts were washed with water and dried over magnesiumsulfate. Filtration and evaporation of the solvent afforded the crudeproduct as a yellow liquid (35 g). The product was further purified byHPLC using a step gradient procedure. Nonpolar material was eluted usingethyl acetate/ammonium hydroxide (98:2) as eluent. The polar product waseluted using the solvent system of acetonitrile/methanol/ammoniumhydroxide (90:8:2) to give pure product as a yellow oil (28 g, 48%).

EXAMPLE 7N-(3-Acetylthio-2-methylpropanoyl)-N-(3'-pyridylmethylene)glycine ethylester

To a solution of N-(3-pyridylmethylene)glycine ethyl ester (6.2 g, 0.032mol) and 3-acetylthio-2-methylpropionic acid (5.2 g, 0.032 mol) inmethylene chloride (100 ml) was added dicyclohexylcarbodiimide (6.8 g,0.0330 mol). Stirring was continued at room temperature overnight.Precipitated dicyclohexylurea was filtered and washed with a smallamount of cold diethyl ether. Evaporation of the filtrate afforded thecrude product as an orange oil (12.5 g). The product was purified byHPLC using a step gradient procedure. Nonpolar material was eluted usingethyl acetate/ammonium hydroxide (98:2) as eluent. The polar product waseluted using the solvent system of acetonitrile/methanol/ammoniumhydroxide (90:8:2) to give pure product as a pale yellow oil (8.4 g,80%).

EXAMPLE 8N-(3-Acetylthio-2-methylpropanoyl)-N-(2'-methylene-1'-ethylpyrrolidine)glycinetert-butyl ester

To a solution of N-(2'-methylene-1'-ethylpyrrolidine)glycine tert-butylester (10.2 g, 0.042 mol) and 3-acetylthio-2-methylpropionic acid (6.8g, 0.042 mol) in dry methylene cloride (200 ml) chilled in an ice bathwas added dicyclohexylcarbodiimide (8.7 g, 0.042 mol). The resultingmixture was stirred overnight at room temperature. Precipitateddicyclohexylurea was filtered and washed with a small amount ofmethylene chloride. Concentration of the filtrate afforded product as adark auburn oil (18.1 g).

EXAMPLE 9N-(3-Mercapto-2-methylpropanoyl)-N-(2'-methylene-1'ethylpyrrolidine)glycine

CrudeN-(3-acetylthio-2-methylpropanoyl)-n-(2'-methylene-1'-ethylpyrrolidine)glycinetert-butyl ester (10.0 g, 0.026 mol) was dissolved in a mixture ofanisole (20 ml) and trifluoroacetic acid (60 ml). The resulting solutionwas stirred at room temperature for two hours. Trifluoroacetic acid wasevaporated in vacuo and the residue was distributed between ethylacetate and saturated aqueous sodium bicarbonate. The aqueousbicarbonate phase was separated and washed twice with ethyl acetate. Theaqueous bicarbonate phase was then saturated with ammonium chloride andplaced in a heavier than water continuous liquid extractor. The productwas continuously extracted into chloroform over 16 hours. The chloroformwas dried over magnesium sulfate, filtered and evaporated to give themercaptan as an oil (4.3 g, 57%). The product was characterized as itsDCHA salt which was prepared in ether to give colorless crystals, m.p.120°-122° C.

EXAMPLE 10 N-(3-Acetylthio-2-methylpropanoyl)-N-furfurylglycine

Crude N-(3-acetylthio-2-methylpropanoyl)-N-furfurylglycine tert-butylester (14.6 g, 0.0407 mol) was dissolved in a mixture of anisole (20 ml)and trifluoroacetic acid (65 ml). The resulting solution was stirred atroom temperature for two hours. The solvent was evaporated in vacuo andthe residue was distributed between ethyl acetate and saturated aqueoussodium bicarbonate. The aqueous bicarbonate extract was washed twicewith ethyl acetate and then acidified cautiously with concentratedhydrochloric acid to pH 4-5. The product was extracted several timesinto chloroform and the chloroform was washed twice with water. Theorganic phase was dried over magnesium sulfate, filtered and evaporatedto give crude product as a pale yellow oil which was purified by HPLCusing the following solvent system: ethyl acetate/n-hexane/acetic acid(40:60:1) to give pure product as a colorless oil (5.5 g, 44.7%). Theproduct was purified by its DCHA salt which was prepared in ether, m.p.140°-141° C.

EXAMPLE 11 N-(3-Mercapto-2-methylpropanoyl)-N-furfurylglycine

Anhydrous ammonia was bubbled for ten minutes through methanol (200 ml)and the resulting ammonia saturated solution was added in one portion toN-(3-acetylthio-2-methylpropanoyl)-N-furfurylglycine (8 g, 0.0264 mol)and the resulting colorless solution was placed under nitrogen. Theresulting solution was stirred at room temperature for one and a halfhours. The solvent was removed in vacuo and the residue was applied to acolumn of AG-50W-X2 (Bio-Rad Laboratories) cation exchange resin andeluted with methanol. Methanol was evaporated and the residue wasdissolved in chloroform. The chloroform was washed once with water anddried over magnesium sulfate. Filtration and evaporation of the solventafforded crude product as an oil which was purified by HPLC using thefollowing solvent system: ethyl acetate/n-hexane/acetic acid (35:60:1),to give pure colorless oil (5.4 g, 80%). The product was characterizedas its DCHA salt, m.p. 150°-153° C.

By following the procedures described in the above examples, thefollowing additional compounds were prepared:

N-(3-Mercapto-2-methylpropanoyl)-N-(furyl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-(5-benzofuryl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-(furfuryl)glycine

N-(3-Mercapto-2,2-dimethylpropanoyl)-N-(3-thienyl)glycine

N-(3-Benzoylthio-2-methylpropanoyl)-N-(3-thiazolyl)glycine

N-(3-Mercapto-3-methylbutanoyl)-N-(2-benzothienyl)glycine

N-(2-Mercapto-2-methylpropanoyl)-N-(4-tetrahydrothiopyranyl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-1-(2-thienyl)ethylglycine

N-(3-Mercapto-2-methylpropanoyl)-N-(3-tetrahydrothienyl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-(N-ethylpiperdine-3-yl)glycine

N-(2-Mercaptomethylbutanoyl)-N-2-(1-indol-3-yl-propyl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-2-methylenethienylglycine

N-(3-Mercapto-2-methylpropanoyl)-β-(2-thienyl)alanine

N-(3-Mercapto-2-methylpropanoyl)-β-(2-pyridyl)alanine

N-(3-Mercapto-2-methylpropanoyl)-N-(4-aminopyridyl)glycine

N-(3-Acetylthio-2-methylpropanoyl)-N-(1-isoquinolyl)glycine

N-(3-Acetylthio-2-methylpropanoyl)-N-(2-pyrimidyl)glycine

N-(3-Acetylthio-2-methylpropanoyl)-N-(2-benzimidazoyl)glycine

N-(3-Mercapto-2-methylpropanoyl)-N-(tetrahydrothiophene-1,1-dioxide3-yl)glycine

The compounds of the present invention have demonstrated potent activity(of the order I₅₀ of 0.017 to 0.030 micromols) in inhibiting theangiotensin converting enzyme (ACEI activity) when tested by the methoddescribed in Science 196, 441-4 (1977). As such, these compounds wouldbe very useful in the treatment of hypertension.

The compounds of the present invention are somewhat structurally relatedto the compounds disclosed in German Offenlengunsschriften No. 2,717,548and 2,753,824. However, the compounds disclosed in these publicationspossess an ACEI activity of about one three-hundredth shown by thecompounds of the present invention.

Table I below lists the ACEI activity of representative compounds of thepresent invention. The I₅₀ value represents the amount in micromolsrequired to give an inhibitive effect of 50% in the tests using theprocedure described in the Science article.

                  TABLE I                                                         ______________________________________                                         ##STR10##                                                                    M                   R.sub.7  I.sub.50                                         ______________________________________                                        Tetrahydrofurfyl    CH.sub.3 CO                                                                            1.4                                              Furfuryl            CH.sub.3 CO                                                                            0.7                                              Furfuryl            H        0.16                                             Tetrahydrofurfuryl  H        0.13                                             1,1-Dioxytetrahydrothienyl                                                                        CH.sub.3 CO                                                                            2.2                                              1,1-Dioxytetrahydrothienyl                                                                        H        0.2                                              Thienylmethyl       CH.sub.3 CO                                                                            0.75                                             N--Ethyl-2-pyrrolidylmethyl                                                                       H        0.47                                             Thienylmethyl       H        0.055                                            ______________________________________                                    

The compounds of the present invention may be administered orally orparenterally in the treatment of hypertension, and it will be within theprofessional judgment and skill of the practitioner to determine theexact amount to be administered.

We claim:
 1. A compound of the structure: ##STR11## whereinR₁,R₂,R₃,R₄,R₅ and R₆ are independently hydrogen, alkyl, alkenylcontaining 2 to 6 carbon atoms, alkynyl containing 2 to 6 carbons atoms,phenyl-alkyl or cycloalkyl containing 3 to 16 carbon atoms,n is aninteger from 0 to 4 inclusive, M is selected from the group consistingof pyridyl, quinolyl or piperidyl, Y is hydroxy, alkoxy, amino,aminoalkanoyl, hydrocarbylaryloxy containing from 6 to 10 carbon atoms,aminoalkoxy, or hydroxyalkoxy, and R₇ is hydrogen, alkanoyl,carboxyalkanoyl, hydroxyalkanoyl, amino-alkanoyl, cyano, amidino,carbalkoxy, ZS, or ##STR12## wherein Z is hydrogen, alkyl,hydroxyalkyl,aminoalkyl or the radical ##STR13## wherein R₁,R₂,R₃,R₄,R₅,R₆,n,M and Yare as described above, and the alkyl groups per se and alkyl moietiesof groups containing an alkyl group, contain 1 to 6 carbon atoms; or,where Y is hydroxy, its nontoxic, pharmaceutically acceptable alkalimetal, alkaline earth metal, or amine salt.
 2. A compound of thestructure ##STR14## wherein R₁, R₂, R₃, R₄, R₅ and R₆ are independentlyhydrogen, lower alkyl, lower alkenyl, lower alkynyl, phenyl-lower alkyl,or cycloalkyl, wherein the lower alkyl, lower alkenyl or lower alkynylgroups have up to 6 carbon atoms and the cycloalkyl groups have from 3to 16 carbon atoms,n is an integer from 0 to 4, M is pyridyl, quinolylor piperidyl, Y is hydroxy, lower alkoxy having up to 6 carbon atoms, oramino, R₇ is hydrogen, lower alkanoyl, ZS or ##STR15## wherein the loweralkanoyl group contains up to 6 carbon atoms, and Z is hydrogen, loweralkyl containing up to 6 carbon atoms, or a radical of the formula##STR16## wherein R₁, R₂, R₃, R₄, R₅, R₆ and Y are as defined above, or,where Y is hydroxy, its nontoxic, pharmaceutically acceptable alkalimetal, alkaline earth metal or amine salt.
 3. A compound according toclaim 2 wherein n is
 1. 4. A compound according to claim 3 wherein Y ishydroxy.
 5. A compound according to claim 4 wherein R₁, R₃, R₄, R₅ andR₆ are hydrogen and R₂ is lower alkyl.
 6. A compound according to claim5 wherein R₂ is methyl.
 7. A method of reducing the blood pressure inmammals having hypertension which comprises administering to saidanimals an effective amount of a compound according to claim 1.